//节流函数
//func 传入的函数，delay 延时时间
export function  debounce(func, delay) {
  let timer = null
  return function (...args) {
    if (timer) {
      clearTimeout(timer)
    }
    timer = setTimeout(() => {
      func.apply(this, args)
    }, delay)
  }

}


export function getRandomArrayElements(arr = [], count = 3) {
  let shuffled = [], i = arr.length
  while (--count > -1) {
    shuffled.push(arr[Math.floor(Math.random() * i)])
  }
  return shuffled;
}


export function formatDate(date, fmt) {
  if (/(y+)/.test(fmt)) {
    fmt = fmt.replace(RegExp.$1, (date.getFullYear() + '').substr(4 - RegExp.$1.length));
  }
  let o = {
    'M+': date.getMonth() + 1,
    'd+': date.getDate(),
    'h+': date.getHours(),
    'm+': date.getMinutes(),
    's+': date.getSeconds()
  };
  for (let k in o) {
    if (new RegExp(`(${k})`).test(fmt)) {
      let str = o[k] + '';
      fmt = fmt.replace(RegExp.$1, (RegExp.$1.length === 1) ? str : padLeftZero(str));
    }
  }
  return fmt;
};

function padLeftZero(str) {
  return ('00' + str).substr(str.length);
};

export function gotoTarget(offset = 0) {
  // 缓冲
  //  setInterval(() => {
    // 再次获取滚动条距顶部高度
    // let osTop = document.documentElement.scrollTop;
    // 用于设置速度差,产生缓慢效果
    // let speed = Math.floor(-osTop / 8);
    document.documentElement.scrollTop = offset;

}
